Significance

Global environmental change is challenging the adaptive capacity of entire ecological communities. Community rescue occurs when populations within a community evolve in response to an environmental stress that was initially lethal to all the constituent organisms. We studied how communities of soil microbes can extend the area they occupy to include conditions that were initially lethal, and how these communities can persist despite the degradation of environmental conditions. Our results suggest that entire communities have the potential to adapt to severe environmental stress. Community rescue is promoted by the initial diversity in the community, is more frequent among communities that have previously experienced intermediate sublethal levels of stress, and is facilitated by the dispersal of organisms across the landscape.

Abstract

The conditions that allow biodiversity to recover following severe environmental degradation are poorly understood. We studied community rescue, the recovery of a viable community through the evolutionary rescue of many populations within an evolving community, in metacommunities of soil microbes adapting to a herbicide. The metacommunities occupied a landscape of crossed spatial gradients of the herbicide (Dalapon) and a resource (glucose), whereas their constituent communities were either isolated or connected by dispersal. The spread of adapted communities across the landscape and the persistence of communities when that landscape was degraded were strongly promoted by dispersal, and the capacity to adapt to lethal stress was also related to community size and initial diversity. After abrupt and lethal stress, community rescue was most frequent in communities that had previously experienced sublethal levels of stress and had been connected by dispersal. Community rescue occurred through the evolutionary rescue of both initially common taxa, which remained common, and of initially rare taxa, which grew to dominate the evolved community. Community rescue may allow productivity and biodiversity to recover from severe environmental degradation.

Footnotes

Author contributions: E.L.-D., A.G., and G.B. designed research; M.K., P.H., and A.L. performed research; E.L.-D. and A.D. analyzed data; and E.L.-D., A.G., and G.B. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

Data deposition: The sequence reported in this paper has been deposited in the European Nucleotide Archive (accession no. ERA445478). Data and analysis scripts are available in the Dryad database (dx.doi.org/10.5061/dryad.65b2g).

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